This invention relates generally to spring assemblies for bedding and furniture foundations for mattresses and seat cushions. Such spring assemblies conventionally consist of a support frame, a wire grid positioned above the support frame, and springs supporting the grid on the frame for yieldable movement under load toward the frame.
Spring assemblies of this type now in use are satisfactory. They consist of metal components such as the springs and the grid and in some cases the frame which are supplied to the bedding or furniture manufacturer for assembly and ultimate sale. In the case of box spring assemblies, various sizes and grades of box spring assemblies are made by the manufacturer and this requires the maintenance by the furniture manufacturer of a large inventory of metal components. There are, therefore, opportunities for improving such spring assemblies particularly from the standpoint of ease of assembly and ease of converting from one grade or size to another.
It is an object of the present invention, therefore, to provide spring assemblies that can be readily assembled with fewer of the usual clips for connecting springs and grids and which teaches the adaptation of a formed wire, limited deflection spring module to a stackable spring assembly system, to thereby accomplish economy of wire, economy of shipping, ease of assembly to a wood frame and versatility of spring patterns. The present invention is thus an improvement on the invention disclosed in the above application.
It is also an object to provide a spring assembly that can be economically preassembled and nested in compact stacks that can readily be shipped by the manufacturer of the metal grids and springs without danger of shifting or entanglement of parts during transit or storage. Each spring assembly consists of a grid unit and a predetermined number of spring modules connected to the grid unit.
In this invention, economy of wire is accomplished with a geometrically unique main spring of "formed wire type". It has a "V" formed base with dual column support on the frame to prevent spring collapse under load. Full spring element deflection is limited to approximately 21/2" which has previously been established as optimum for useful surface dynamics. Stable column support, as displayed in this invention, prevents system failure when shock loads are applied. Previous stackable spring assemblies have been of non-limited deflection design.
The present invention allows nested bundles of 100 spring assemblies or more that can be palletized and stacked in what ever height and configuration is best suited to the transit vehicle. This is possible because the contact points, between nested assemblies, become more stable when the weight of additional assemblies is applied. These then form a series of support columns, in a "honeycomb" fashion, that distribute and stabilize additional stacks and prevent entanglement of nests.
Another feature of the current invention is a formed wire corner spring that incorporates all the features of the described formed wire main spring, with changes made to the bar, lever and mounting geometry to provide optimum platform support and upholstery support unique to the corners of the unit.
Because the spring assemblies are shipped preassembled in virtually solid stacks, a larger number of completed spring assemblies can be shipped (approximately 2,800-3,000/Truckload) than previous knockdown type box spring assemblies (approximately 2,200-2,500) where grids and springs are shipped in separate bundles and cartons for subsequent assembly. Further the spring assemblies of this invention are ready to attach to the wood frame, upon arrival to the customer, with no sub-assembly operations required.
It is a further object of this invention to provide a spring assembly which includes a spring module that can readily be adapted to the manufacture of spring assemblies in a variety of sizes and a variety of spring densities in the assembly.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawing.